1. Technical Field
The present invention relates to an inductively coupled plasma apparatus.
2. Related Art
Generally, an inductively coupled plasma apparatus includes a spiral type antenna installed at an upper outer portion of a reaction chamber, in which a plasma etching process is carried out, by interposing dielectric material therebetween. In addition, RF induced power is applied to the spiral antenna in order to generate an electric field in the reaction chamber, thereby creating plasma. Such an inductively coupled plasma apparatus has a simple structure as compared with an ECR (electron cyclotron resonance) plasma apparatus or an HWEP (Helicon-wave exited plasma) apparatus, so the inductively coupled plasma apparatus may easily generate plasma over a large area. For this reason, the inductively coupled plasma apparatus has been applied to various fields and research into such inductively coupled plasma apparatuses has been continuously carried out.
FIG. 1a shows a structure of a chamber 300′ of a conventional inductively coupled plasma apparatus. Hereinafter, the structure of the chamber 300′ of the conventional inductively coupled plasma apparatus will be described.
An antenna source 100′ is aligned at an uppermost part of the conventional inductively coupled plasma apparatus such that the antenna source 100′ is exposed to an exterior. In addition, a dielectric member 200′ is interposed between the antenna source 100′ and the chamber 300′ so as to insulate the antenna source 100′ from the chamber 300′ while maintaining a vacuum state. An object 400′ to be etched is positioned at a bottom of the chamber 300′.
FIG. 1b shows a spiral antenna structure used for the chamber of the inductively coupled plasma apparatus.
However, such a spiral antenna structure shown in FIG. 1b may cause problems if a size and an area of the object 400′ to be etched become enlarged.
Firstly, if the chamber has a large area, the size and thickness of the dielectric member for maintaining a vacuum state between the antenna source and the chamber become increased. Thus, a manufacturing cost is increased and efficiency is lowered because a distance between the antenna source and plasma becomes more distant.
In addition, since a length of the antenna source becomes long as the chamber has a large area, power loss may occur due to resistance of an antenna and etching uniformity may be deteriorated due to unevenness of plasma.
Furthermore, if a power supply capable of applying power of 13.56 MHz is used, a standing wave effect (two wave pulses having the same amplitude and frequency are traveling in opposition to each other and overlapped with each other so that the wave pulses look like standing waves) may occur at a half wavelength portion of the antenna source, so that it is impossible to further enlarge the size of the chamber.